More than two years after an estimated 20-meter class meteor fragmented high over the Russian city of Chelyabinsk, new data reported by NASA researchers this week reveals that over a four billion year timeframe the meteors orbital parent body itself had likely been geologically-impacted as many as a dozen times. <\/p>\n
Two 15- to 20-gram samples of the Chelyabinsk meteorite that NASA obtained from Russia over a year ago reveal a broad range of information about the meteors mineralogy, bulk composition and age, as noted at the Lunar and Planetary Science Conference in Houston. <\/p>\n
These same fragments came off the path of the fireball somewhere around the middle of its trajectory through Earths atmosphere, Kevin Righter, the lead for meteoritic sample analysis and the Antarctic meteorite curator at NASAs Johnson Space Center, told Forbes. He says the fragments pieces from the outer portion of the meteor itself which streaked across the Russian sky on February 15, 2013 are typical of more stony-type meteorites and made up of some 90 percent silicate; five percent sulfide; and five percent iron-nickel. The original crystallization age of the parent body asteroid, says Righter, might be 4.5 billion years old. But in this case, he says, they found multiple ages using three or four different chronologic detection techniques. <\/p>\n
Righter says he and colleagues found evidence for about a dozen different parent-body impact events in pieces of the Chelyabinsk meteorite they studied; ranging from 300 million years ago to as recently as 27 million years ago. <\/p>\n
People look at what scientists believe to be a chunk of the Chelyabinsk meteor, recovered from Chebarkul Lake near Chelyabinsk, about 1500 kilometers (930 miles) east of Moscow, Russia, Wednesday, Oct. 16, 2013. Scientists on Wednesday recovered what could be the largest part of this meteor from Chebarkul Lake outside the city. They weighed it using a giant steelyard balance, which displayed 570 kilograms (1,256 pounds) before it broke. (AP Photo\/Alexander Firsov) <\/p>\n
Geologically, thats very young, said Righter. Ages determined on ordinary chondrites can be as old as over 4 billion years old. But theres hardly ever any evidence for these young ages. <\/p>\n
The meteor, which initially exploded in the Russian atmosphere at some 29 km in altitude, wreaked widespread destruction and injury in and around the city of Chelyabinsk. But how much of the Chelyabinsk meteoritic material actually made it to the ground? <\/p>\n
The main so-called terminal mass of the asteroid was a couple of meters in diameter and weighed over 500 kilograms, planetary scientist Paul Abell, also at NASAs Johnson Space Center, told Forbes. <\/p>\n
What hope do we have of actually identifying the parent body of this Chelyabinsk object in the near-Earth vicinity? <\/p>\n
Finding the parent body of a near Earth asteroid, says Abell, is really tough because these asteroids are in chaotic orbits. The best we can do, he said, is to try and make a compositional link. <\/p>\n
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NASA Surprised By Chelyabinsk Russian Meteor Fragments<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" More than two years after an estimated 20-meter class meteor fragmented high over the Russian city of Chelyabinsk, new data reported by NASA researchers this week reveals that over a four billion year timeframe the meteors orbital parent body itself had likely been geologically-impacted as many as a dozen times. Two 15- to 20-gram samples of the Chelyabinsk meteorite that NASA obtained from Russia over a year ago reveal a broad range of information about the meteors mineralogy, bulk composition and age, as noted at the Lunar and Planetary Science Conference in Houston. Continue reading